Neuromechanical Simulation of Human Postural Sway in the Sagittal Plane Based on a Hybrid Triple Inverted Pendulum Model and State-Dependent Intermittent Neural Control

Objective: This study introduces a novel neuromechanical model that employs a hybrid triple inverted pendulum (HTIP) framework combined with state-dependent intermittent control to simulate human quiet stance in the sagittal plane. Methods: The proposed neuromechanical model integrates the biomechanics of the ankle, knee, and hip joints, focusing on the stabilization of the body's center of mass (CoM) rather than controlling each joint individually. Unlike computational models that require precise joint control, the central nervous system maintains posture by simplifying neural control mechanisms. Specifically, the state-dependent control strategy activates neural feedback only as the CoM approaches the stability boundaries. Results: Experimental validation against real-world data demonstrated that the model can accurately replicate natural postural sway patterns in the sagittal plane. Conclusion: The model provides a computationally efficient mechanism and a realistic simulation of human posture control, addressing a long-standing challenge in neuromechanical modeling of human quiet stance. Significance: This study enhances understanding and simulation capability offers significant new insights for developing targeted interventions for individuals with impairments in postural control.